50% are liberal and 50% are conservative
And 100% of Americans are one or the other. While simultaneously being moderate or extreme on the other scale.
By definition. Whatever the spectrum of opinion, those are the two ways it's customarily chopped-up and labelled--either two or three bins of data. But I don't think it really means anything.
Are you saying that the ideological makeup of the GOP hasn't changed? Surely not. The exodus of RINOs forced out of the party hasn't been offset by an influx of new moderates. The Republican party has gotten seriously more conservative in the last decade. That's not a matter of arbitrarily redefining the scale, that's a real change. Isn't it?